Helicobacter pylori (H. pylori) is a gram-negative bacterium belonging to the genus Spirillum isolated from the gastric mucous membrane of a patient suffering from chronic gastritis and cultivated (Marshall B. J., Warren J. R., Lancet, 1984, 1:1311-1315). It has already been elucidated that such H. pylori is closely related not only to the crises of chronic gastritis and peptic ulcers, but also to the crises of serious or advanced gastric disease such as gastric cancers and gastric malignant lymphoma (Peek R. M. Jr., Blaser M. J., Nature. Rev. Cancer, 2002, 2:28-37).
It has been said that the total number of the persons infected with H. pylori would reach almost a half of the total population in all of the world, but these gastric diseases are not always advanced even to serious conditions thereof in all of the infected persons. This fact clearly indicates that the gastric mucous membrane in itself would be provided with the mechanism of protecting the same from the infection of the bacterium, H. pylori. 
H. pylori inhabits in the superficial mucus secreted from the surface layer of the gastric mucous, but never inhabits in the mucous and the glandular mucus secreted from the mucous deep layer. This glandular mucus inherently contains a sugar chain derived from O-glycan having an alpha-N-acetyl-glucosaminyl residue (alpha GlcNAc residue) at the terminal thereof. For this reason, the foregoing fact would suggest that the sugar chain may protect the gastric mucous from the infection with H. pylori. 
An article of Kawakubo M. et al., Science, 2004, 305:1003-1006 discloses the effect of alpha GlcNAc residue on the proliferation of H. pylori. This article likewise discloses that glycoproteins which are each linked with a core binary-branched O-glycan having an alpha GlcNAc bond at the un-reduced terminal (GlcNAc alpha 1-4Gal beta 1-4GlcNAc beta 1-6(GlcNAc alpha 1-4Gal beta 1-3)GalNAc-R) can substantially inhibit the proliferation and mobility of H. pylori and can likewise induce considerable changes such as the elongation of bacterial cells and the formation of asymmetric contours and the fragmentation thereof. A series of these changes are not observed at all in case of the O-glycan free of any alpha GlcNAc residue. In addition, this article also states that the glycosyl cholesterol components (CGL) which exist in the surface layer of the bacterial cells are significantly reduced, as has been deduced from the results obtained by the morphological observation of H. pylori in the presence of sugar chains each carrying the foregoing alpha GlcNAc residue.
H. pylori essentially requires CGL for the survival thereof, but it cannot synthesize the same by itself (Hirai Y. et al., J. Bacteriol., 1995, 177:5327-5333). Accordingly, it would be believed that H. pylori takes in cholesterols from the external world and adds glucose to the region in the proximity to the membrane of the bacterial cell to thus construct the cell wall. In this respect, it would thus be estimated that the foregoing sugar chain carrying the alpha GlcNAc residue has an ability to inhibit the construction of such a cell wall. However, it requires the use of multiple steps and great expense to chemically or enzymatically synthesize the foregoing core binary-branched O-glycan having an alpha GlcNAc bond at the un-reduced terminal and therefore, the chemical or enzymatic synthesis of the O-glycan is not considered to be practicable.
Moreover, Japanese Patent Provisional Publication No. 2003-517015 discloses substances having an ability of being linked with H. pylori, which have sugar chains each including smaller Gal beta 3GlcNAc or Gal beta 3GalNAc, but a method for the preparation of these substances is quite complicated and therefore, the method never permits the mass production of the same.
On the other hand, the presently used methods for treating patients infected with H. pylori are not ones which make use of these sugar chains, but they mainly comprise the step of exterminating bacterial cells through the simultaneous use of the following three kinds of drugs: a kind of proton pump-inhibitor and two kinds of antibiotics. In the medical treatment with which the three kinds of drugs are combined, problems further arise such that this treatment may induce the generation of resistant bacteria to thus cause the recurrence of the infectious disease and that they may cause side effects.
For this reason, there has been desired for the development of a proliferation inhibitor of H. pylori comprising alpha GlcNAc residue-containing sugar chain derivative, which never exerts any adverse effect on the human body such as a side effect, can be produced in commercial quantity and can easily be prepared.